Femoral Neck Fractures
Fractured neck of femur patients take up significant numbers of beds in hospitals in all the developed nations, as elderly people develop low bone density, especially women after the menopause. Less commonly stress fractures can occur in anyone who puts greatly increased stresses through their hips such as running athletes and soldiers who are in a much younger age group. Trauma such as a fall onto the side of the hip can cause this fracture in almost any age group as can pathological conditions in the area secondary to tumours.
The circulatory anatomy of the femoral head and neck have long convinced specialists in orthopaedics that it is vital to restore the bony alignment of the fragments to avoid the risk of avascular necrosis (AVN) in the head of the femur. A fracture can cause loss of the blood supply in the femoral head, allowing it to die and collapse which causes significant problems and requires operation. Keeping patients immobilised in a hip plaster spica was used initially until Smith-Petersen developed a more predictable internal fixation in the 1930s. The Richards Screw Plate uses compression applied to the fracture site by a sliding fixation technique.
Compressive and shear stresses pass across the femoral necks when we do normal things such as walk but they can be greatly increased by involvement in sports such as jumping, high athletic performance and jogging. The bodyweight can be amplified five or six times across the hip in fairly standard activities such as stair climbing, let alone sport. The groin, the lateral hip and the anterior thigh are the typical areas of presentation of hip related pain from many pathological changes as well as stress fractures, which may worsen to complete fractures with or without displacement with its risks and complications.
In younger healthy people who exert abnormally high demands on normal bone the bone structures can fail mechanically due to the excessive stresses imposed on them. In older people, especially post menopausal women, normal stresses are imposed on bone which is not able to cope with them, bone with pathological changes due to insufficiency of the bone from osteoporosis or other metabolic abnormality. Oestrogen maintains the turnover and health of bone strength and without it bones become more brittle, either in older women or female athletes in high intensity training.
A femoral stress fracture should at least be suspected in an athlete who presents with hip pain after a significant increase in level of activity, with the typical picture worsened with activity and relieved by rest. As x-rays may not show anything in stress fractures bone scanning is used as a more sensitive measure. Much more common is an older person who jars themselves, twists on the hip or falls, resulting in a fracture of the femoral neck. Diagnostic indications are pain in the hip, groin or thigh, a shortened leg, lateral rotation of the leg and an inability to weight bear.
Transverse fractures of the femoral neck have approximately a 10-15 percent risk of displacement with its accompanying possibilities of avascular necrosis. These fractures need operative fixation and the question arises about the correct surgical management. Joint replacement or internal fixation is the choice and this depends on the anatomical placement of the fracture. If the fracture is sub-capital, directly under the head, then the blood supply is potentially affected especially if the fracture is displaced, making a Thompson hemi-arthroplasty or total hip replacement a better option.
It is common for femoral neck fractures to be undisplaced and compacted, in other words the fragments have been compressed together and are stable under load. This makes conservative rather than surgical management more appropriate. Other fractures are mechanically unstable because they are under tension of the fragments to separate and displace, needing surgical fixation with one of many devices for upper femoral fixation. Trochanteric, sub-trochanteric and lower neck fractures can come more commonly into this category.
Once the fracture is replaced or fixed the patient is allowed 24 hours to recover medically then the physiotherapist and an assistant will check the operative instructions, review the patient's observations and get the patient up weight bearing with a frame or crutches.